Bodily cancers are commonly treated using radiation therapy, which employs radiation to kill cancer cells. One form of radiation therapy is brachytherapy. The treatment of brachytherapy places the source of radiation in direct contact with the afflicted tissue. A common brachytherapy treatment is the implantation of radioactive seeds in the prostate gland to kill prostate cancer cells. The physician employs tools such as ultrasounds, computerized axial tomography (“CAT”) scans, and X-ray images in concert with dose-planning computer software programs to evaluate the medical condition of the patient. The physician constructs an optimal treatment plan to evenly distribute radiation throughout the tissue. Proper seed placement is important for controlling the distribution of radiation evenly throughout the entire prostate gland. Placing the radioactive seeds too close together may result in a portion of the prostate receiving too much radiation. Not placing enough seeds in portions of the tissue may result in a region in which the strength of the radiation is insufficient to kill cancer cells.
The physician may insert seeds of the same or different radioactive strengths in pre-selected locations of the tissue. The seeds are inserted into the tissue through an implantation needle, also known as a brachytherapy needle. Multiple brachytherapy needles are required to insert the seeds into multiple locations of the tissue. Each brachytherapy needle inserts a plurality of seeds. An average brachytherapy treatment involves the implantation of approximately 80 to 100 seeds. One way physicians can achieve the axial seed-to-seed spacing required by the treatment plan is to place non-radioactive spacers between the radioactive seeds.
One technique for implanting the seeds involves manually loading the seeds one by one into brachytherapy needles along with spacers in the order prescribed by the treatment plan. The physician then inserts a loaded brachytherapy needle into a specific area of tissue to be treated. A pushrod is guided into the channel of the brachytherapy needle. The physician withdraws the brachytherapy needle while holding the pushrod in place. The seeds are pushed out of the needle and remain inside the afflicted tissue. Multiple rows of seeds and spacers are used to treat an area of tissue, with each position in a row requiring a different brachytherapy needle loaded with seeds and spacers as specified by the physician's plan. Most treatment plans require twenty or more needles loaded with various combinations of seeds and spacers. The management of twenty or more loaded needles presents organizational and management issues associated with the handling of such a large number of needles and includes the inherent risk of handling radioactive materials.
Needles which are loaded prior to the operation must be plugged to prevent the seeds from spilling out during transport or operating room setup. The needles themselves provide limited radiation shielding, requiring the needles to be packaged in a shielded container once loaded.
To place the seeds in the tissue according to the physician's plan, the needle may be releasably attached to a fixed base member (template). The needle is movable within a plurality of positions with respect to the base member with the plurality of positions corresponding to the locations in which the physician desires placement of the seeds and spacers. Those skilled in the art will understand the use of templates and needle grids in the administration treatments in brachytherapy.
The seeds and spacers are small and difficult to handle. The radioactive seeds are a hazardous material and prolonged contact with the needles containing the radioactive seeds is not desirable. Loading seeds and spacers into the individual brachytherapy needles is a time consuming process that increases the time that the medical staff is exposed. The needle loading process must be repeated for each needle used in the treatment. After the needles are loaded, identifying the arrangement of seeds and spacers in the needle and the strength of the seeds requires that the needles be unloaded, inspected, and reloaded. The loaded needles require a shielded container for transport. The seeds may also fall out of the needle, for example due to plug failure. This causes the medical staff to locate, reload, and resterlize the radioactive seeds. Repeated handling of the radioactive seeds by the medical staff increases exposure time.
A technique exists using cartridges to insert the seeds and spacers into the brachytherapy needle. The seeds and spacers are placed in the desired order in a cartridge, which then detachably couples to the brachytherapy needle. The physician then transfers the seeds and spacers from the cartridge into the brachytherapy needle and removes the cartridge from the needle. The brachytherapy needle can then either be loaded into a shielded transport container or, if loaded in the operating room, inserted directly into the afflicted tissue. The physician guides the pushrod into the channel of the brachytherapy needle. The physician then slowly withdraws the brachytherapy needle while holding the pushrod in place. The seeds are pushed out of the needle and remain in a row inside the afflicted tissue. Multiple rows of seeds and spacers are commonly used to treat an area of tissue. Each position in a row requires a different cartridge preloaded to match the treatment plan parameters, requiring the medical staff to handle a different cartridge for each needle used.
One technique involves placing all of the radioactive seeds in a cartridge and manually injecting the seeds in the patient during a treatment. The spacing of the seeds is achieved by withdrawing the needle and injecting the seeds at spaced intervals as the needle is withdrawn. The spacing of the seeds is achieved manually without the benefit of any spacers.
Another technique exists for ensuring proper seed placement and distribution. The radioactive seeds are coupled to form a chain. The manufacturer provides the physician with assembled chains of ten seeds separated by standard spacing. Each chain arrives in a shielded package. The physician removes the chain from the shielded packaging. The physician cuts the chain to match the prescribed treatment plan. Each cut chain is then loaded into an individual brachytherapy needle. The brachytherapy needle inserts into the afflicted tissue. The physician guides the pushrod into the channel of the brachytherapy needle. The physician then slowly withdraws the brachytherapy needle while the holding the pushrod in place. The seed chain is pushed out of the needle and remains in the afflicted tissue. Multiple chains of seeds are used to treat an area of tissue. Each chain must be implanted individually in a different location of the tissue. The physician spends additional time manipulating each individual chain increasing exposure time to the radioactive seeds.